In recent years, the increased numbers of pixels in digital cameras and digital movie cameras have necessitated miniaturization of cell sizes in CCD structures, CMOS structures, and the like. However, miniaturized cell sizes introduce a physical decrease in the geometric area in which light is received, thus lowering the amount of received light. Therefore, what is needed in the future is imaging structures for introducing an increase, even if only a little, in the efficiency of light utilization.
Patent Document 1 proposes an imaging apparatus without color filters which is meant to provide an improved efficiency of light utilization. Light entering the imaging apparatus passes through a plate-like transparent spectroscopic portion which has a higher refractive index than do the surroundings, whereby 0th order light and ±1st order light of respectively different wavelengths occur. It is designed so that the resultant 0th order light and ±1st order light enter respectively different photodetectors. The proposal is to, by using such a transparent spectroscopic portion, enhance the efficiency of light utilization over that of conventional imaging apparatuses in which color filters are employed.
Patent Document 2 discloses an inner-layer lens as a converging device in an imaging apparatus, where light convergence is enhanced through a lens effect. Patent Document 3 discloses an optical waveguide, as a converging device in an imaging apparatus.